frc::TrapezoidProfile< Distance > Class Template Reference

A trapezoid-shaped velocity profile. More...

#include <frc/trajectory/TrapezoidProfile.h>

Classes
class	Constraints
	Profile constraints. More...
class	State
	Profile state. More...

Public Types
using	Distance_t = units::unit_t< Distance >
using	Velocity = units::compound_unit< Distance, units::inverse< units::seconds > >
using	Velocity_t = units::unit_t< Velocity >
using	Acceleration = units::compound_unit< Velocity, units::inverse< units::seconds > >
using	Acceleration_t = units::unit_t< Acceleration >

Public Member Functions
	TrapezoidProfile (Constraints constraints)
	Constructs a TrapezoidProfile. More...
	TrapezoidProfile (Constraints constraints, State goal, State initial=State{Distance_t{0}, Velocity_t{0}})
	Constructs a TrapezoidProfile. More...
	TrapezoidProfile (const TrapezoidProfile &)=default
TrapezoidProfile &	operator= (const TrapezoidProfile &)=default
	TrapezoidProfile (TrapezoidProfile &&)=default
TrapezoidProfile &	operator= (TrapezoidProfile &&)=default
State	Calculate (units::second_t t) const
	Calculates the position and velocity for the profile at a time t where the current state is at time t = 0. More...
State	Calculate (units::second_t t, State current, State goal)
	Calculates the position and velocity for the profile at a time t where the current state is at time t = 0. More...
units::second_t	TimeLeftUntil (Distance_t target) const
	Returns the time left until a target distance in the profile is reached. More...
units::second_t	TotalTime () const
	Returns the total time the profile takes to reach the goal. More...
bool	IsFinished (units::second_t t) const
	Returns true if the profile has reached the goal. More...

Detailed Description

template<class Distance>
class frc::TrapezoidProfile< Distance >

A trapezoid-shaped velocity profile.

While this class can be used for a profiled movement from start to finish, the intended usage is to filter a reference's dynamics based on trapezoidal velocity constraints. To compute the reference obeying this constraint, do the following.

Initialization:

TrapezoidProfile::Constraints constraints{kMaxV, kMaxA};
double previousProfiledReference = initialReference;
TrapezoidProfile profile{constraints};

Run on update:

previousProfiledReference = profile.Calculate(timeSincePreviousUpdate,
                                              previousProfiledReference,
                                              unprofiledReference);

where unprofiledReference is free to change between calls. Note that when the unprofiled reference is within the constraints, Calculate() returns the unprofiled reference unchanged.

Otherwise, a timer can be started to provide monotonic values for Calculate() and to determine when the profile has completed via IsFinished().

Member Typedef Documentation

Acceleration

template<class Distance >

using frc::TrapezoidProfile< Distance >::Acceleration = units::compound_unit<Velocity, units::inverse<units::seconds> >

Acceleration_t

template<class Distance >

using frc::TrapezoidProfile< Distance >::Acceleration_t = units::unit_t<Acceleration>

Distance_t

template<class Distance >

using frc::TrapezoidProfile< Distance >::Distance_t = units::unit_t<Distance>

Velocity

template<class Distance >

using frc::TrapezoidProfile< Distance >::Velocity = units::compound_unit<Distance, units::inverse<units::seconds> >

Velocity_t

template<class Distance >

using frc::TrapezoidProfile< Distance >::Velocity_t = units::unit_t<Velocity>

Constructor & Destructor Documentation

TrapezoidProfile() [1/4]

template<class Distance >

frc::TrapezoidProfile< Distance >::TrapezoidProfile

(

Constraints

constraints

)

Constructs a TrapezoidProfile.

Parameters

constraints

The constraints on the profile, like maximum velocity.

TrapezoidProfile() [2/4]

template<class Distance >

frc::TrapezoidProfile< Distance >::TrapezoidProfile	(	Constraints	constraints,
		State	goal,
		State	initial = State{Distance_t{0}, Velocity_t{0}}
	)

Constructs a TrapezoidProfile.

Parameters

constraints	The constraints on the profile, like maximum velocity.
goal	The desired state when the profile is complete.
initial	The initial state (usually the current state).

Deprecated:

Pass the desired and current state into calculate instead of constructing a new TrapezoidProfile with the desired and current state

TrapezoidProfile() [3/4]

template<class Distance >

frc::TrapezoidProfile< Distance >::TrapezoidProfile ( const TrapezoidProfile< Distance > &  )

default

TrapezoidProfile() [4/4]

template<class Distance >

frc::TrapezoidProfile< Distance >::TrapezoidProfile ( TrapezoidProfile< Distance > &&  )

default

Member Function Documentation

Calculate() [1/2]

template<class Distance >

TrapezoidProfile< Distance >::State frc::TrapezoidProfile< Distance >::Calculate

(

units::second_t

t

)

const

Calculates the position and velocity for the profile at a time t where the current state is at time t = 0.

Parameters

t	How long to advance from the current state toward the desired state.

Returns

The position and velocity of the profile at time t.

Deprecated:

Pass the desired and current state into calculate instead of constructing a new TrapezoidProfile with the desired and current state

Calculate() [2/2]

template<class Distance >

TrapezoidProfile< Distance >::State frc::TrapezoidProfile< Distance >::Calculate	(	units::second_t	t,
		State	current,
		State	goal
	)

Calculates the position and velocity for the profile at a time t where the current state is at time t = 0.

Parameters

t	How long to advance from the current state toward the desired state.
current	The current state.
goal	The desired state when the profile is complete.

Returns

The position and velocity of the profile at time t.

IsFinished()

template<class Distance >

bool frc::TrapezoidProfile< Distance >::IsFinished ( units::second_t  t ) const

inline

Returns true if the profile has reached the goal.

The profile has reached the goal if the time since the profile started has exceeded the profile's total time.

Parameters

t	The time since the beginning of the profile.

Returns

True if the profile has reached the goal.

operator=() [1/2]

template<class Distance >

TrapezoidProfile & frc::TrapezoidProfile< Distance >::operator= ( const TrapezoidProfile< Distance > &  )

default

operator=() [2/2]

template<class Distance >

TrapezoidProfile & frc::TrapezoidProfile< Distance >::operator= ( TrapezoidProfile< Distance > &&  )

default

TimeLeftUntil()

template<class Distance >

units::second_t frc::TrapezoidProfile< Distance >::TimeLeftUntil

(

Distance_t

target

)

const

Returns the time left until a target distance in the profile is reached.

Parameters

target

The target distance.

Returns

The time left until a target distance in the profile is reached.

TotalTime()

template<class Distance >

units::second_t frc::TrapezoidProfile< Distance >::TotalTime ( ) const

inline

Returns the total time the profile takes to reach the goal.

Returns

The total time the profile takes to reach the goal.

---

The documentation for this class was generated from the following files:

• frc/trajectory/TrapezoidProfile.h
• frc/trajectory/TrapezoidProfile.inc